Process of effecting chemical reactions with by-product carbon from cellulose purification



Patentefi Apr, teas,

htthtlt GHARLES B. JACGBS, M WMINGTQN, DMJAWARE, ASSIGNOE 'liQ E 1.33% EON? DE NEMGUES t t CQMPANY, @l WILMINGTON, DELAWME, A GQEPOMTION Gil nuts- WME.

PMCEES GE EFFECTINGEHEMICAL REACTIONS WETE BY-PRQDUUT CAEBON' ENE CELLULOSE JPUEIFICATIUN.

It's Drawing. Application filecl July 10, 191%, serial 369,926. nenewcai Sseptcmber as, 1923.

To all whom it may COW/067%.

Be it known that l, Guanine B. Jecoss, a citizen of the United States, and a resident of Wilmington, in the county of New Castle and State of Delaware, have inventecl a cer-' tain new and useful Process of Efiecting Chemical Reactions-with By-Procluct Carbon from Cellulose Purification, of which the following is a specification.

This invention relates to processes involving thermochemical reactions in which the element carbon is an active constituent of the reacting materials, by virtue of its power to combine chemically, under the proper conditions, with other elements to form either volatile, or non-volatile chemical compounrls, and pertains especially to processes or this character in which the carbon constituting one of the reacting materials is particularly adapted for such reactions by reason of its purity and chemical activity.

in carrying out thermo-chemical reactions in general in which carbon is one of the alltive elements involved, it is always desirable to select a term of carbon as free from nonb iolatile or mineral impurities as practica- There is a wide variation in the chemical activity of the rlifierent varieties of amorphous carbon, the harder and denser varieties being much less active than the soft and more porous varieties.

In a general sense purity and chemical activity are closely related in the amorphous varieties of carbon the urer the carbon used the greater is the spec and yield of the reaction as well as the purity of the product.

lnsuch operations as the reduction of iron ancl various metals from their ores by carbon, the presence of certain non-volatile or mineral impurities such as silica, alumina, lime, etc, is more or less unimportant since these impurities are made to pass 0E in the slag and exert no deleterious efiect upon the uality of the product, and for such operatrons relatively cheap forms of carbon, such as anthracite coal or coke from bituminous coal, constitute suitable forms of carbon for the purpose.

In the thermochemical treatment of alkali and alkaline-earth compounds with carbon, on the other hand, the presence of such impurities as silica, alumina, sulphur, phosghorus, iron, etc, in coal or colic not only etracts from the actual yielrl of the operation by forming undesirable side products with the alkal and alkline-earth compounds, but frequently results in the con tamination of the finished product with impurities dificult or impossible to remove.

The reduction oi zinc oxide to metallic zinc and the manufacture of certain fies of ultrainarine, where the presence o even small uantities of iron prevents the production or the proper color in the finisheoi material, are further instances of thermochemical operations in which the use oi pure carbon is desirable Unfortunately, in many thermochemical 0 stations of which the above cited; examp es serve as eneral illustrations, the use of iiues, in which tree or cemental nitrogen is cause& to combine directly with carbon anti alkali metal commands to form alkali metal cyanicles as described in re applications, Serial No. $39,801 ans Seria ll c, 279,802, filecl in the U. 5. Patent @fice, February 28, 1919, l have discovered a term of carbon which constitutes a oesicleratum for thermochemical reactions in general, which involve can hon as a reactive element.

This material results from. various vege table fibers such as cotton, esparto, straw, was, etc, in the process of purifying the cellulose oi the fibers from the incrusting substances such as lignin, resins, and other organic substances which are soluble in cans tic solution.

The principal source of this material is ice from the manufacture of wood pol by the sols process where a mixture of car on and calcium carbonate constitutes one of the 'a leaching tan straw fibers. When derived from wood the carbon is (produced in the following manner: The woo either deciduous. of coniferous,

is digested with a solution of sodium hydroxide. This solution in reducing the wood to pulp ,combines with the incrusting substances of the wood, forming a series of soluble organic substances.

After the digestion is completed the pulp is blown into a tank equipped with a perforated bottom, and the so-called black liquor, containing the incrusting substances of the wood in solution, is drained 0E. The pulp is also washed with hot Water, and the washings added to the original liquor. This liquor is evaporated in a vacuum evaporator until it has attained a density of 35 to 40 degrees Baum, when it is discharged to an incinerator. The incinerator is similar to the rotary furnaces usually employed in cement I manufacture, lined with firebrick and equipped with a furnace at one end. It is rotated at a speed of about one revolution per minute. The thickened liquor from the evaporator enters the incinerator at the end opposite the furnace, and is metby the hot gases and flames from the same. As it Works its way toward the outlet end it is further evaporated by the hot gases and is finally ignited by the flames from the fur: nace. at this point the ash as discharged from the incinerator containing from 10 to 15% of unburned carbon, resulting from the inciner ation of the soluble incrusting substances of the wood contained in the evaporated liquor, would be causticized with lime, the resulting mixture leached to remove most of the sodium hydroxide formed, and the residue comprising carbon mixed with calcium carbonate thrown away.

I have discovered that if the ash from the incinerator be first leached and washed with water to remove sddium carbonate and any other soluble materials that me be present, instead of being first causticize there is obtained as a residue a form of carbon characterized by possessing a chemical activity and power 0 adsorption in a remarkably high degree.

According to m fprocess the ash is immedlately conve e rom the incinerator to and here the soda ash formed from the caustic in the evaporation process, is dissolved and the carbon washed thoroughly with hot water. When the washing is com lete there is lefta residue of carbon containing usually from about 2% to 4% of Na CO, which is suificiently are for many urposes. A- continuation o the washing Wlll render the carbonsubstantially ash-free, except for small amounts, a fraction of a per cent, of silica and alumina.

A much larger yield of carbon may be obtained by calcinlng' in a closed type of If ordinary practice were followed,

kiln in which case little or none of the carbon resulting from the cracking or breaking down of the resins, lignin, and alkalisoluble cellulose is consumed by oxidation.

This carbon which is described and claimed in my application, Serial No. 312,- 610, filed concurrently herewith, I have found to be far superior in thermo-chemical reactions to even the finest grades of charcoal, petroleum coke and similar forms of carbon of about equal purity. This is due to its greater chemical activity.

Its aifinity for oxygen is so great that when it is warmed in a current of air it ignites and begins to glow at temperatures below those at which powdered charcoal is affected. The temperature is so low that a small metal crucible containing the material may be held in the bare hand without discomfort until the ignition begins.

The organic constituents of wood which are dissolved by the alkali used in the soda process include certain forms of cellulose which are soluble in sodium hydroxide solution, and various resins. The proportions of cellulose soluble in sodium hydroxide solution, and of resins, varies considerably in different kinds of wood. The sodium hydroxide-soluble cellulose is usually present in substantial proportions; the carbon obtained from wood in the above-described manner may therefore be said to consist essentially of alkali-soluble-cellulose carbon and alkali-soluble-woo d-resin carbon.

The great affinity of this form of carbon for oxygen. at temperatures below those at which the ordinary forms of carbon combine with oxygen makes it an efiicient reducing agentby materially lowering the temperatyre ordinarily required for the reduction of Various difficulty reducible oxides and ma even bring certain reductions with car on now only possible at temperatures of the electric furnace into the temperature ranges attainable in gas, oil or coal fired furnaces;

Although I have described above in detail the manufacture of carbon from the alkalisoluble constituents of wood, it is to be understood that b the expression carbon obtainable by t iermally decomposing the alkali-soluble constituents of wood, I mean to include carbon derived in like manner from cotton, esparto, straw, and equivalent ye etable fibers. or technical numerous economical advantages over other forms ofjcarbon. It is produced in "a finely divided condition and requires no grinding previous to mixing with charges for thermochemical operations. It is a cheap waste product and can be obtained at a much lower cost than even coal or ordinary coke from bituminous coal. Its great chemical activity produces-higher yields and shortens the time.

urposes the material has dill neaaosc required for thermochemical operations, thus increasing the plant output of finished product.

On account of its low cost it is ap licable to practically all thermochemical operations in which carbon is used, and its chemical activity and purity make it especially adapted to such operations as the treatment of alkali and alkaline'earth compounds, the reduction of zinc compounds,

the manufacture of ultramarine, of carbon bisulphide and tetrachloride and many similar operations where purity and activity of the carbon are desirable, but heretofore have not been practicable on account of the cost of carbon substantially free from nonvolatile or mineral impurities.

As will be clear from the above, my process from one as set comprises decomposing or reducing a su stance whose molecule contains oxygen, such as zinc oxide or sodium carbonate, by subjecting to a high temperature a mixture comprising said substance and alkali-soluble-cellulose carbon usually mixed with alkali-solublewood-resin carbon. My process also comprises efiecting a reaction between a substance whose molecule contains oxygen, tor example sodium carbonate, barium hydroxide or carbonate, or other oxygen-containing compound of an alkali-forming metal, and a substance Whose molecule does not contain oxygen, for ex ample nitrogen, by bringing said substances in contact with the b product carbon of high activit hereinbe ore described, maidtained at a i h temperature.

In the speci 0 practical application which I have made of this form of carbon in thermo-chemical operations, viz: the production of alkali metal oyanides as described in my applications, Serial No. 279,801 and Serial No. 279,802 filed in the U. S. Patent Ofice, February 28, 1919, in which the followinE-g equation expresms the generally accep empirical reaction involved:

it will be seen that the carbon in the reaction forms both a volatile and a non-volatile chemical compound and that in this case it is desirable to have the activity oi the carbon greater than that possessed by ordinary carbon.

This process oil producing alkali-metal cyanides, stated generically, comprises heating in contact with nitro en a mixture contaming a'n alkali-metal alide, a reducible compound of a carbideor nitride-forming metal such as iron, a compound of an alkalimetal other than a halide as for example an alkaliunetal carbonate or hydroxide, and alkali-solublecelluloee carbon, to a temperature sufiicient to edect a reaction between the carbon, nitrogen, and the alkali-metal carbonate or hydroxide, to form an alkali-metal cyanide. A high yield may be obtained even if the iron oxide be omitted, but the yield is less than where iron oxide is used.

Typical examples of processes of makin metal cyanides involving the application 0 this highly reactive carbon are as follows?- Exam 1e 1.Where sodium chloride or fluoride is to be the chief accelerating agent, a suitable retort is charged with a mixture of approximately thirty-nine per cent (39%) of sodium carbonate, twenty-one per cent (21%) of sodium chloride and forty per cent l0%) of carbon produced as hereinbefore described, so that the retort will be about two-thirds full. The retort is then placed in a furnace and connected with a source of nitrogen. The charge is then heated to a temperature between 800 and 970 C, any volatile matter or gaseous reduction products being allowed to escape so that a porous mixture remains in the retort. As soon as a temperature between 800 and 970 C. has been reached the nitrogen is allowed to How through the charge in the retort, the valve connections being so adjusted that an absolute pressure of about two atmospheres is obtained inside the retort. A satisfactory yield is obtained when working under ordinary atmospheric pressure, but the yield is increased somewhat by using an increased pressure. In view of the high temperature it is not practicable to exceed an absolute pressure of about 35 pounds. The opera ion is continued fona predetermined time until gas samples taken from the gas escaping from the retort show little or no carbon monoxide, which indicates that the reaction is finished. In case producer gas is a source of nitrogen the gas samples show a decided fall-oil of carbon monoxide with a corresponding increase in nitrogen when the reaction approaches completion. lhe nitrogen is then shut on and the retort sealed, removed from the furnace, and cooled to room temperature; the contents may then be removed without danger of injurious oxidation.

Ewample $2.-When iron oxide is used in conjunction with sodium chloride or fluoride as the chief accelerating agent the charge is made up of forty per cent (40%) or sodium carbonate, forty per cent (e070) oi the highly reactive carbon described above, fifteen per cent (15%) of oxide of iron, and live per cent (5%) of sodium fluoride. These proportions may vary considerably; thus with 40% of sodium carbonate and about 35 to to parts of carbon, "for example, ll may use as little as three (3) parts of sodium fluoride and nine (9) parts of iron oxide; 1 consider it preferable, however, with the above mentioned parts or carbonate and carbon to use greater amounts or halide and iron oxide, such as from five to twelve (5-12) parts of sodium fluoride,

and from thirty-five to fifteen (35-1 5) parts of iron oxide.

The charge made up as above described is placed in a suitable retort and subjected to the same treatment as that described in Example 1, the temperature being maintained preferably at from 925 to 950 0., under an absolute pressure of about 23 to 30 pounds.

When carrying out the processes described in the above examples with charges of identical composition except that 40% by weight yields and shortening the time required for the completion of the reaction to one-half of that usually required, by the substitution of this particular form of carbon will be obvious to those familiar with the art.

I have found the application of this form of carbon to thermo-chemical operations differing in many ways from those mentioned above'to be advantageous; thus I may form it into briquettes with various other materials to carry out various thermo-chemical reactions; or I may make compositions of it with various inert materials to obtain an extended reaction surface of carbon for use as a catalyzer, as for instance in the manufacture of phosgenc, or to carry out thermochemical reactions in which gases or vapors or liquids are required to be brought into contact with large,surface areas of chemically active carbon.

Having thus described my invention what I claim is:

1. The process of decomposing an oxygencontaining metal compound which comprises subjecting to a high temperature a mixture containing said metal compound and alkalisoluble-cellulose carbon.

2. The process of decomposing an oxygencontaining metal compound which comprises subjecting to a high temperature with exclusion of gaseous oxygen amixture containing said metal compound and alkalisoluble-cellulose carbon.

3. The process of separating oxygen from a substance containing chemically bound oxygen which comprises heating said substance to a high temperature in contact with alkali-soluble cellulose carbon.

4. The process of separating ox gen from a substance containing chemica ly bound oxygen which comprises heating said substance to a high temperature in contact with carbon obtainable by thermally decomposing the alkali-soluble constituents of wood.

5. The process of effecting reactions between a substance whose molecule contains oxygen and a substance whose molecule does not contain oxygen which comprises bringing said substances in contact with alkalisoluble cellulose carbon at a high temperature.

v 6. The process of eiiecting reactions be-v tween nitrogen and an oxygen-containing compound of an alkali-forming metal which comprises bringing nitrogen in contact with a mixture comprising said oxygen contaiiring alkali-forming metal compound and alkali-soluble cellulose carbon while maintaining said mixture at a high temperature.

7. The process of effecting reactions between nitrogen and an oxygen-containing compound of an alkali-forming metal which comprises bringing nitrogen in contactvwith a mixture comprising said oxygen containing alkali-forming metal compound, an alkali-metal halide, and alkali-soluble cellulose carbon while maintaining said mixture at a high temperature.

8. The process of effecting reactions between nitrogen and an alkali-metal carbonate which com rises bringing nitrogen in con tact with a mlxture comprising said alkalimetal carbonate, analkali-metal halide, and

wood, while maintaining-said mixture at a high temperature.

10. The process of effecting reactions between nitrogen and an oxygen-containin compound of an alkali-forming metal whic comprises bringing nitrogen in contact with a mixture comprising said oxygen containing alkali-forming metal compound, a finel' divided substance comprising iron, an a kali-metal halide, and alkall-soluble-cellulose carbon while maintaining said mixture at a high temperature.

11. The process of producing an alkalimetal cyanide which comprises heating in contact with nitrogen a mlxturecontainin an alkali-metal halide, a reducible compound of a carbide-forming metal, a compound of an alkali-metal other than a halide, and alkali-soluble cellulose carbon, to a temperature sufiicient to efiect'a reaction between the carbon, nitrogen, and the last mentioned alkali-metal compound to form an alkalimetal cyanide.

12. The process of making sodium cyanposing the alkali-soluble constituents of ide which comprises heating in contact with nitrogen a mixture containing a sodium halide iron oxide, sodium carbonate, and alkali-soluble cellulose carbon, to a temperature suificient to eifect a reaction between the carbon, nitrogen, and the sodium carbonate to form sodium cyanide.

13. The process of producing an alkalimetal cyanide which comprises heating in contact with nitrogen a mixture containing an alkali-metal halide, a reducible compound of a carbide-forming metal, a compound of an alkali-metal other than a halide, and carbon obtainable by thermally decomposing the alkali-soluble constituents of wood, to a temperature suflicient to effect a reaction between the carbon, nitrogen, and the last mentioned alkali-metal compound to form an alkali-metal cyanide.

14. The process of making sodium cyanide, which comprises heating in contact with a nitrogen-bearing gas a mixture containing sodium fluoride, a reducible compound of a carbide-forming metal, sodium carbonate, and carbon obtainable by thermally decomposing the alkali-soluble con stituents of Wood, to a temperature sufiicient to effect a reaction between the nitrogen, carbon and sodium carbonate to form sodium cyanide.

15. The process of making an alkali-metal cyanide, which comprises heating in contact with a nitrogen-bearing gas a mixture containing an alkali-metal halide, a finely divided substance comprising iron, a compound of an alkali-metal other than ahalide, and carbon obtainable by thermally decomposing the alkali-soluble constituents of wood, to a temperature sutficient to efiect a reaction between the carbon, nitrogen and the alkali-metal compound to form an alkali-metal cyanide. I

16. The process of making an alkali-meta cyanide, which comprises making a mixture containing an alkali-metal halide,a reducible compound of a carbide-forming metal, a compound of an alkali-metal other than a halide, and carbon obtainable by thermally decomposing the alkali-soluble constituents of wood, heatin the'mixture in a closed retort provided with an exit for. the escape of gaseous products to a sufficient temperature to expel gaseous reduction products from the reducible compound of the carbide-formin metal to render the mixture porous, and su jecting the porous mixture to the action of nitrogen, at a temperature sufiicient to effect a. reaction between the carbon, nitrogen and the alkali-metal compound to form an alkali-metal cyanide.

17 The process of making an alkali-metal cyanide, which comprises making a mixture of an alkali-metal halide, oxide of iron, a compound of an alkali-metal other than a halide, and carbon obtainable by thermally decomposing the alkali-soluble constituents of wood, heating the mixture in a closed retort provided with an exit for the escape of gaseous products to a sufiicient temperature to expel gaseous reduction products from the oxide of iron to render the mixture porous, and subjecting the porous mixture to the action of a nitrogen-bearing gas, at a temperature suflicient to eiiect a reaction between the carbon, nitrogen and the alkalimetal compound to form an alkali-metal cyanide.

18. The process of making an alkali-metal cyanide, which comprises making a mixture of an alkali-metal halide, a reducible compound ofa carbide-forming metal, a compound of an alkali-metal other than a halide, and carbon obtainable by thermally decomposing the alkali-soluble constituents of wood, heating the mixture in a closed -retort provided with an exit for the escape of gaseous products to a temperature of from about 850 to 950 C., and subjecting the heated mixture to the action of nitrogen, substantially as described.

19. The process of making an alkali-metal cyanide, which comprises passing nitrogen gas under an absolute pressure of from about 23 to pounds per square inch in contact with a mixture containing an alkalimetal halide, a reducible compound of a carbide-forming metal, a compound of an alkali-metal other than a halide, and carbon obtainable by thermally decomposing the alkali-soluble constituents of wood, while maintaining said mixture at a temperature sufficient to effect a reaction between the carbon, nitrogen and alkali-metal compound to form an alkali-metal cyanide.

20. The process of making an alkali-meta cyanide which comprises heating in contact with nitrogen a mixture containing from 5 to 12 parts of an alkali-metal halide, from 35 to 15 parts of iron oxide, about 40 parts of an alkali-metal compound other than a halide and from 35 to parts of carbon obtainable by thermally decomposing the alkali-soluble constituents of wood, to a temperature sufiicient to efi'ect a reaction between the carbon,'nitrogen and the alkalimetal compound to form an alkali-metal cyanide.

In testimonyv whereof I afiix my signature.

CHARLES B. JACOBS. 

